[client][modules] implement default behavior for module initialization
[client][userlist] initialize at the right time

Fixes #137
[client][userlist] always place local thumbnail first
[client][userlist] reimplement multi-column thumbnails

Fixes #147
[client][userlist] reinstore hover controls right behavior
Merge pull request #148 from Paulloz/multicolumnthumbnails
Merge pull request #145 from Paulloz/patch135